240 The Commercial Apple Industry 



which arsenate of lead is being used 3 and even 4 pounds 

 paste to 56 gallons of water. Where the codlin-moth is 

 becoming a more serious menace, it is thought that by 

 increasing the dosage, quicker killing effects may be 

 secured and the loss from later stings may be reduced. 



Paris green is an arsenical poison which has been largely 

 superseded by arsenate of lead, the latter having proved 

 more adhesive, more compatible with other spray materials 

 and less likely to cause burning. Paris green is not widely 

 used in any commercial apple region. 



Calcium arsenate is being tried out in many parts of 

 the United States and, although more or less in an experi- 

 mental state of development, has given some promise, par- 

 ticularly when used on apples under eastern conditions 

 where codlin-moth infestation is not serious. The pow- 

 dered forms contain 42 to 45 per cent of arsenic-oxide and 

 the paste forms 17 to 20 per cent. When employed alone 

 in the Northwest, some burning resulted. The addition of 

 paste lime at the rate of 2 or 3 pounds of stone lime to 50 

 gallons of water is considered a wise precaution against 

 burning. Combination of lime-sulfur, summer strength, 

 with calcium arsenate has thus far proved satisfactory. 

 Calcium arsenate has not been widely employed in any 

 commercial apple region, although it is being tested by 

 many growers at present. Commercial forms lack the 

 smoothness and fineness which characterizes the well- 

 known brands of arsenate. It is not improbable that the 

 physical properties of commercial calcium arsenate can be 

 greatly improved. Experiments have thus far given some 

 promise. Complete results of thorough trial and demon- 

 stration will be awaited with interest. Although it has 

 not yet demonstrated the quick-killing properties of lead, 



